As electronic technology increases, so also does the demand for advances in digital computing technology. One such driving factor includes advances in the technology of devices that convert analog signals to digital signals, and vice verse, such as for implementation in communications devices. A variety of electronic devices that manipulate analog and digital signals can include resonant tunneling diodes (RTDs). An RTD is a non-linear electronic component that can transition from a positive differential resistance region at a lower range of voltages to a positive differential resistance region at a higher range of voltages in a circuit when the voltage across its terminals reaches or exceeds a critical peak value via a quantum tunneling effect.
FIG. 1 illustrates an example of a voltage/current graph 10 of a typical RTD. The graph 10 is a plot of current (I) on the vertical axis versus voltage (V) on the horizontal axis. The current (I) is thus a current flow through the RTD and the voltage (V) is thus a voltage across the RTD.
The graph 10 demonstrates a first region 12, which is a lower positive differential resistance region, that is defined between zero volts and a peak voltage VP. Thus, in the first region 12, the current (I) exhibits a substantially linear relationship relative to an increase in the voltage (V), with a slight leveling near the peak voltage VP to a maximum magnitude of I1. The graph 10 also demonstrates a second region 14, which is a negative differential resistance region, that is defined between the peak voltage VP and a valley voltage VV. The second region 14 is a negative differential resistance region based on a decrease in the current from a magnitude of I1 at the peak voltage VP to a lesser magnitude I2 at the valley voltage VV. The second region 14 can be unstable in a circuit, such that the RTD may not be able to maintain a voltage (V) between the peak voltage VP and the valley voltage VV. The graph 10 also includes a third region 16, which is a higher positive differential resistance region, that begins from the valley voltage VV and increases linearly.
A sequencing device, such as an analog-to-digital converter (ADC), can be designed with a circuit that includes one or more RTDs arranged in series. The one or more RTDs can each be like-sized RTDs with a substantially identical dynamic impedance, such that the circuit can form a series voltage divider. Thus, in response to an input voltage that is applied to the series RTDs, one or more of the RTDs transition, or “trigger”, from the peak voltage VP to the valley voltage VV to provide a quantization of the input voltage. However, since the dynamic impedance is approximately the same for the RTDs, upon applying the input voltage to the series RTDs, two or more of the RTDs can inadvertently be provided with enough voltage to trigger approximately simultaneously. As a result, there may be an error in the quantization of the input voltage.